Optimized composite downhole tool for well completion

ABSTRACT

A composite cone assembly for use with a frac or bridge plug system is discussed herein having shaped outer contours and the strength needed for high pressure applications but with reduced machining requirements by forming part of the cone assembly from a high strength fiber material and the contoured surface from molding, such as from injection molding or compression molding.

BACKGROUND

In oil and gas well completion operations, frac or bridge plugs are necessary for zonal isolation and multi-zone hydraulic fracturing processes. The advantages of frac and bridge plugs made primarily from composite materials is well established since these products significantly reduce drill-out (removal) time compared to all metallic frac and bridge plugs. However, as drilling for oil and gas extends deeper and/or fracking pressures increase, composite frac and bridge plugs are now expected to meet higher operating pressures and temperatures. Higher temperatures and pressures put severe stresses on the composite frac or bridge plug components that are thought to already operate at or near their operating limits. It is therefore necessary to optimize the design of the composite frac or bridge plug components to meet still yet higher operational requirements with necessary strength. It is also necessary to optimize downhole tools for lower cost since they are an expendable item in well completion.

A typical frac or bridge plug is configured to be positioned in and seals a well casing pipe by actuating serrated wedge slips that dig into the inner wall of the casing as the frac or bridge plug is set. There are typically 4-8 serrated wedge slip elements that are forced out against the well pipe casing by tapered cones located on the frac or bridge plug mandrel that have flat notches machined into the outer surface. The notches in the cone act as a guide for the slips and provide the inclined wedge necessary to force the slips into the well pipe inner wall when the frac or bridge plug is set.

As a result of these complex outer surface features, both the upper and lower cones of a frac or bridge plug are difficult to make and therefore expensive. The lower cone in a typical frac or bridge plug is more highly loaded in operation than the upper cone. For this reason, more expensive materials and processes are required to make the cones but especially the lower one.

While upper cones can be compression molded or injection molded from advanced fiber-filled polymers, the lower cone is typically made from wrapped high strength fiberglass cloth pre-impregnated with epoxy resin in order to be strong enough to resist the compressive forces of the inclined wedges that keep the frac or bridge plug from being pushed down the well during fracking. A typical high strength lower cone is made out of a billet of fiberglass material that is first formed by wrapping pre-preg fiberglass cloth material and curing it with heat. The billet is then machined into the final lower cone shape that includes faceted surfaces for the wedge slips to interface with. The machining of the fiberglass billet is particularly expensive and difficult due to the abrasive nature of the composite cone material.

SUMMARY

It is therefore necessary to optimize the design of the composite frac or bridge plug components to meet higher operational requirements with necessary strength. It is also necessary to optimize downhole tools for lower cost since they are an expendable item in well completion.

It would be desirable to have a frac or bridge plug cone assembly that is entirely molded and did not require machining of the outer shape and dimensions yet meet the strength requirements for deeper and deeper fracking operations. Additionally it would be desirable to have a cone assembly that could be made by semi-automated means versus hand lay-up.

An aspect of the present disclosure includes a cone assembly for use with a frac plug or bridge plug system made by molding a composite reinforcing structural member with an injection molded or compression molded outer shell with optional faceted outer surface or contoured outer surface formed, at least in part, by the molding process.

Another aspect of the present device and system is a composite material cone structural insert element made by filament winding or by wrapping woven cloth and polymeric resin materials and positioned inside an outer cone section to form a cone assembly that achieves the desired faceted outer shape with little or no machining.

A still further feature of the present disclosure is a frac or bridge plug cone assembly made by bonding a composite reinforcing structural member into an injection molded outer cone shell that has the desired faceted features with little or no machining.

The disclosure also includes a cone assembly made by press fitting a composite reinforcing structural member into an injection molded outer cone shell that has the desired cone assembly shape for use with a frac plug or bridge plug system with little or no machining.

The present disclosure also includes a mandrel having a seal member disposed thereon and a slip member located adjacent the injection molded outer cone shell for operating as a frac plug or a bridge plug system.

Aspects of the present disclosure also include methods for using and for forming a cone assembly and a frac plug or bridge plug system. In one example, a method of manufacturing a cone assembly for use with a frac plug or bridge plug system is disclosed. The method can comprise utilizing more than one composite material, forming an imler composite structural component having a tapered outer body, and forming an outer cone section by molding.

The method, wherein the molding step is either injection molding or compression molding a polymer material around a filament would fiber material.

The method, wherein the molding step for the outer cone section is performed separately or away from the inner composite structural component.

The method, wherein the forming step for the inner composite structural element comprises winding a fiber material around a mandrel.

The method, wherein the cone assembly is formed by injection molding or compression molding an outer cone section over the inner composite structural component made by a filament winding process and wherein the outer cone section and the inner composite structural component are each sized and shaped for optimized load conditions during use.

A still further feature of the present disclosure is a filament wound structural composite ring to handle the compressive crushing loads imposed by the wedge slips.

A still yet further feature of the present disclosure is a molded outer shell with the necessary material compressive strength to handle the wedge slip interface stresses.

The present disclosure is also understood to include a cone assembly for use with a frac plug or bridge plug system, said cone assembly comprising an imler reinforcing structural member made from a composite material and having a bore and an outer shell disposed over the inner reinforcing structural member, said outer shell being made by injection molding or compression molding and has a shaped outer molded surface; and wherein the outer shell has a first end of a first diameter and a second end of a second diameter, which is larger than the first diameter.

The cone assembly wherein the inner reinforcing structural member may be made by filament winding or by wrapping woven cloth and polymeric resin materials.

The cone assembly wherein the outer shell has a plurality of spaced apart fins each extending radially outwardly from the shaped outer molded surface and wherein at least one tapered surface is located between two adjacent fins.

The cone assembly wherein the inner reinforcing structural member can be located inside a mold and the outer shell is formed over the inner reinforcing structural member while inside the mold.

The cone assembly wherein the outer shell can be bonded to the inner reinforcing structural member.

The cone assembly wherein the outer shell may have a press fit with the inner reinforcing structural member.

The cone assembly can further comprise a mandrel located in the bore of the inner reinforcing structural member and wherein a seal member and a slip member are located on the mandrel.

The present disclosure is still further understood to include a method of manufacturing a cone assembly for use with a frac plug or bridge plug system. The method can comprise the steps of utilizing more than one composite material; forming an inner composite structural component having a tapered outer body with a first composite material, molding an outer cone section for use with the inner composite structural, said molding comprising the use of a second composite material; wherein the inner composite structural component has a first open end, a second open, and a bore extending therebetween; and wherein the outer cone section has a tapered outer surface section formed by molding.

The method wherein the molding step can either be injection molding or compression molding a polymer material around a filament would fiber material.

The method wherein the molding step can be performed separately from the inner composite structural component.

The method wherein the forming step for the inner composite structural element can include winding a fiber material around a mandrel.

The method wherein the cone assembly may be formed by injection molding or compression molding the outer cone section over the inner composite structural component, which may be made by a filament winding process.

The method wherein the outer cone section can include a plurality of spaced apart fins and wherein a tapered surface section can be located between two of the fins.

The method can further comprise placing the inner composite structural component inside a mold before molding the outer cone section over the inner composite structural component.

The method can further comprise the step of placing an elongated mandrel through the bore of the inner composite structural component and placing one or more slip pads in abutting contact with the outer cone section.

The method can further comprise bonding the inner composite structural component and the outer cone section together.

The method can further comprise press fitting the inner composite structural component and the outer cone section together.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present device, system, and method will become appreciated as the same becomes better understood with reference to the specification, claims and appended drawings wherein:

FIG. 1 is a perspective view of a cone assembly provided in accordance with aspects of the present device, system, and method.

FIG. 2 is a perspective view of an insert or inner cone structural element provided in accordance with aspects of the present disclosure.

FIG. 3 is a schematic view of the inner cone structural element of FIG. 2 located in a molding tool for molding an outer shell or outer cone section over the inner cone structural element.

FIG. 4 is perspective view of the outer shell or cone assembly of FIG. 1, which may be separately formed and subsequently assembled with the insert element of FIG. 2 or by injection molding or compression molding directly over the inner cone structural element.

FIG. 5 is a schematic side view of the cone assembly of FIG. 1.

FIG. 6 is a schematic front view of the cone assembly of FIG. 1.

FIG. 7 is a schematic cross-sectional side view of the cone assembly of FIG. 6 taken at line 7-7.

FIG. 8 is a frac plug or bridge plug system having one or more cone assemblies of the present disclosure for activating adjacent slip members.

DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of the presently preferred embodiments of cone assemblies and frac and bridge plug systems provided in accordance with aspects of the present device, system, and method and is not intended to represent the only forms in which the present device, system, and method may be constructed or utilized. The description sets forth the features and the steps for constructing and using the embodiments of the present device, system, and method in connection with the illustrated embodiments. It is to be understood, however, that the same or equivalent functions and structures may be accomplished by different embodiments that are also intended to be encompassed within the spirit and scope of the present disclosure. As denoted elsewhere herein, like element numbers are intended to indicate like or similar elements or features.

FIG. 1 is a perspective view of a cone assembly 40 for use with a downhole bridge plug or frac plug system to activate adjacent slip pads, also known as gripping members or slip members. As further discussed below, the cone assembly 40 comprises an outer cone section 20 and an inner cone structural element 10 (see also FIG. 2), which is termed inner relative to the outer cone section 20 but may be referred to as a first cone assembly and a second cone assembly, respectively. In one example, the outer cone section 20 is co-molded or over-molded to the cone structural element 10. In another example, the outer cone section 20 is compression molded over the cone structural element 10. In still another example, the outer cone section 20 is made from a high strength fiber-filled polymer material and then machined to receive the cone structural element 10, which is wound from a high modulus fiber material, such as carbon fiber, as further discussed below.

As shown, the cone assembly 40 comprises a first end 42 comprising an opening 44 and a second end 46 comprising an opening 48 defining a bore 50 therebetween sized for mounting over a mandrel of a downhole bridge plug or frac plug system. The cone assembly 40 comprises a plurality of tapered sections 54 on the taper body 30 and are each located between adjacent pairs of facets or fins 52. A flat landing section 56 is formed adjacent the open end or end wall 58 of each fin 52 for mating arrangement with the slip element on the downhole bridge plug or frac plug system. Depending on the shape, size, or contour of the mating slip element to be activated by the cone assembly 40, the number of fins 52, the location of the fins, and the contour of the tapered section 54 may change. Thus, aspects of the present device, system, and method are understood to not be limited to the exact embodiment shown in FIG. 1 and that variations in the number of fins, location of fins, contour and tapered sections are within the scope of the present disclosure. In some examples, the end walls 58 of the plurality of fins 52 extend further towards the first end 42. In still other examples, the end walls 58 are flushed with the end first end 42.

FIG. 2 is a perspective view of a cone structural element 10 for use with the outer cone section 20 provided in accordance with aspects of the present device, system, and method. In one example, the cone structural element 10 is formed by filament winding a carbon fiber/epoxy composite cone structure, which comprises a first end 12, a second end 14, and a tapered body section 16 extending therebetween. In an example, a constant internal diameter between the first end 12 and the second end 14 is provided, which defines an increasing wall thickness on the structural element 10 extending from the first end 12 towards the generally constant outer section 18 near the second end 14. The thickness from the transition point 17 towards the second end 14 of the generally constant outer section 18 has a generally constant thickness, although variations may be practiced without deviating from aspects of the present disclosure. For example, the outer contour may have a single slope extending from the first end 12 to the second end 14. In another example, the outer contour has a complex slope from the first end 12 to the second 14 that can vary to enable bonding, securing, and/or varied support at different locations for the outer cone section 20. As shown, the structural element 10 is sufficiently thick for use as an actuating cone element of a bridge plug or frac plug assembly, such as being sufficiently thick to withstand compressive forces in the order of several tons of pressure.

The cone structural element 10 preferably has a fiber orientation of roughly +/−85 degrees although other angles may be useable for forming the cone structural element for certain applications, such as from +/−45 degrees to 90 degrees. While carbon fiber is a preferred material due to its high modulus property, other fibers may be suitable for forming the composite structural element 10, such as fiberglass. Additionally, resins other than epoxy may also be suitable for forming the composite structural element 10, such as phenolic resin. Woven cloth fiber forms may also be used in lieu of filament winding the structural cone element 10.

After the filament wound composite structural element 10 is cured and cut to length, post cure machining to the outside of the filament wound insert 10 may be performed to smooth, round, or further shape the composite structural element. In another example, no machining is performed to the composite structural element 10 after it has been formed other than cutting to length. In yet another example, grit blast is optionally performed to the outer surface of the structural insert 10 to promote adhesion with other components, as further discussed below. In still yet other embodiment, the outer cone shape body section 16 or the constant outer diameter section 18 may incorporate protrusions, projections or recessed sections to facilitate attaching the structural insert element 10 with the outer cone section 20, as further discussed below.

Thus, an aspect of the present device, system, and method is understood to include a composite structural element 10 for use in a cone assembly comprising a body section have a first end with a first opening and a second end with a second opening defining a bore therebetween and wherein the bore comprises a generally constant inside diameter, within acceptable manufacturing tolerances. The present disclosure is further understood to include a composite structural element 10 comprising a tapered outside body section that increases in thickness form the first end towards the second end. As described, the composite structural element 10 can be made from a filament winding process, such as with carbon fiber. In another example, the composite structural element 10 can be made from woven cloth fiber instead of filament winding. As further discussed below, the structural element 10 may be pressed fit or bonded to an outer cone section to form a cone assembly, or both. In another example, the structural element 10 may be used as an insert inside a mold housing or tool for co-molding or over-molding with a fiber-filled polymer material to form the outer cone section 20 around the inner composite structural element 10.

With reference now to FIG. 3, the composite structural element 10 is shown placed into an injection mold or compression molding tool 22 to over-mold or co-mold the composite structural element 10 to f0lm a completed cone assembly 40 (FIG. 1). In one example, a high strength fiber-filled polymer (either thermosetting or thermoplastic) is injected into the molding tool 22 through one or more gates or ports 24 to build up around the composite structural element 10, such as to form an outer cone section 20 around the composite structural element 10. The injection mold or compression mold 22 is formed with several faceted shape cavities 26 and a tapered main cavity 28 for forming the tapered body 30 of the outer cone section 20 and the plurality of facets or fins 52. The facets 52 are configured for interfacing with wedge slip elements of the downhole tool assembly and therefore can vary in shape, size, number, orientation, etc. depending on the wedge slip elements to be incorporated in the downhole tool assembly. For example, in some embodiments, the facets may be omitted altogether and/or the particular angle chosen for the tapered body 30 may vary in degree and in continuity, such as being formed with distinct or separate tapered sections.

In another embodiment, rather than injection molding the molding tool 22 with a high strength fiber-filled polymer to form the outer cone section 20 over the inner structural element 10, a blob of curable fiber-filled polymer is filled inside the mold assembly 22 and compression molded over the inner structural element 10. In still yet another embodiment, the mold assembly 22 may have a single large cavity for co-molding or over-molding the outer cone section 20 to the structural insert element 10 into a billet. After curing, the billet may be machined, such as with a CNC or milling machine, to form various facets, fins, and/or shaped surfaces to form the cone assembly 40.

With reference now to FIG. 4 in addition to FIG. 2, the composite structural element 10 may be machined to shape in accordance with another aspect of the present disclosure for use with the outer cone section 20 to produce a cone assembly having at least two different composite materials. For example, the machined composite structural element 10 may be inserted into the second end of the outer cone section 20 and bonded, press fit thereto, or both to form the cone assembly 40 of FIG. 1. In another example, the structural cone element 10 is formed and cut to length but not machined. Instead, the bore at the second end 46 of the outer cone section 20 is machined to receive the structural cone element 10. For example, the inside bore of the second end 46 may be machined to accept the composite structural shaped element 10.

FIG. 5 is a side view of the cone assembly 40 of FIG. 1 with dashed lines, which represent the tapered side walls 60 of the plurality of fins 52. The tapered side walls 60 are better shown the perspective view of FIG. 1. The tapered walls are configured to accommodate adjacent tapered surfaces of adjacent slip members when mounted onto a bridge plug or frag plug assembly.

FIG. 6 is a front view of the cone assembly 40 of FIG. 5.

FIG. 7 is a cross-sectional side view of the cone assembly 40 of FIG. 6 taken along line 7-7. The cross-hatchings of FIG. 7 clearly show the cone shape composite structural component 10 positioned inside the outer cone section 20 to reinforce the overall structural integrity of the cone assembly 40. As discussed above, the composite structural component 10 is made from a filament wound fiber material, such as carbon fiber, with high modulus properties to provide increased resistance to shear and compressive forces experienced in high pressure applications compared to moldable polymer material, as an example. However, moldable high strength fiber-filled polymer (either thermosetting or thermoplastic) allows the cone assembly 40 to be formed with various features, such as contours, angles, shapes, fins 52, other extensions, and/or recesses, more easily and economically by molding them rather than machining them after forming an intermediate cone assembly, such as forming a generally cylindrical billet with a sufficiently thick sidewall to then machine to produce a finished cone assembly. In one example, these various features can be created by forming a mold housing or tool, such as the molding tool 22 of FIG. 2, having shaped cavities for folming negative impressions of the shaped cavities.

Thus, an aspect of the present disclosure is understood to include a cone assembly comprising an inner composite structural element made from a high modulus composite material that reinforces an outer cone assembly made from a relatively lower modulus propeliy material having a tapered body section for acting against a slip member in a downhole assembly. In a particular example, the inner composite structural element is made by filament winding a fiber material around a mandrel and the outer cone section is made from injection molding or compression molding an injectable polymer material inside a molding housing or tool.

FIG. 8 is a bridge plug or frac plug system 62 provided in accordance with aspects of the present device, system, and method. As shown, the system 62 includes a mandrel 64, an upper support member 66, an upper slip pad 68, an upper cone member or assembly 40, two intermediate support members 72, a seal member 70, a lower cone member 40′, a lower slip pad 74, and a head member 76. Bridge plug and frac plug systems can vary from manufacturer to manufacturer and thus the specific components and number of components described can vary. In general, the system 62 is configured to seal a well bore of a downhole metal casing to isolate a section of the casing upstream of the seal member 70 so that blasting or high pressure fluid can be introduced into the casing to open the well during fracking operation. The seal member 70 seals against the casing by axially compressing the seal member 70 to cause it to expand radially against the inner wall of the casing to seal there against. To keep the seal from moving, the upper slip pad 68 and the lower slip pad 74 are caused to slide over the tapered surfaces 54 (FIG. 1) of the tapered body 30 of the cone assembly 40. This action causes the gripping members 78 of the upper and lower slip pads 68, 74 to project radially outwardly relative to the longitudinal length of the plug system 62 to bite against the interior wall surfaces of the well to keep the seal member stationarily fixed within the well. In another example, because the upper cone assembly 40 is exposed to lower operating pressure than the lower cone assembly 40′, a lower cost singularly formed fiber-filled upper cone assembly may optionally be used rather than a multi-part cone assembly having a composite structural element.

In another aspect of the present disclosure, a frac plug or bridge plug system comprising a mandrel, a slip pad disposed on the mandrel comprising a plurality of gripping members, and a cone assembly positioned adjacent the slip pad and comprising a tapered body section, an outer cone section made of a first material, and a composite structural component 10 comprising a second stronger material than the first material is provided. In a particular example, the inner composite structural component 10 is made from a fiber wound filament material. In another example, the composite structural component 10 is made from a woven cloth material. In yet other examples, the cone assembly is one of the cone assembly discussed elsewhere herein and optionally by one of the methods discussed elsewhere herein.

Although limited embodiments of the cone assemblies and frac and bridge plug systems and their components have been specifically described and illustrated herein, many modifications and variations will be apparent to those skilled in the art. Accordingly, it is to be understood that the cone assemblies, frac and bridge plug systems and their components constructed according to principles of the disclosed device, system, and method may be embodied other than as specifically described herein. The disclosure is also defined in the following claims. 

What is claimed is:
 1. A method of manufacturing a sub-assembly for use with a frac plug or bridge plug system comprising the steps: forming an inner composite structural component having a tapered outer body with a first composite material, molding an outer cone section for use with the inner composite structural component, said molding comprising using a second composite material; wherein the inner composite structural component has a first open end, a second open end, and a bore extending between the first and second open ends; and wherein the outer cone section has a tapered outer surface section formed by molding.
 2. The method of claim 1, wherein the molding step is either injection molding or compression molding a polymer material around a filament wound fiber material.
 3. The method of claim 1, wherein the molding step is performed separately from the inner composite structural component.
 4. The method of claim 1, wherein the forming step for the inner composite structural component comprises winding a fiber material around a mandrel.
 5. The method of claim 1, wherein the sub-assembly is formed by injection molding or compression molding the outer cone section over the inner composite structural component, which is made by a filament winding process.
 6. The method of claim 5, wherein the outer cone section has a plurality of spaced apart fins and wherein a tapered surface section is located between two of the fins.
 7. The method of claim 5, further comprising placing the inner composite structural component inside a mold before molding the outer cone section over the inner composite structural component.
 8. The method of claim 5, further comprising placing an elongated mandrel through the bore of the inner composite structural component and placing one or more slip pads in abutting contact with the outer cone section.
 9. The method of claim 5, further comprising bonding the inner composite structural component and the outer cone section together.
 10. The method of claim 5, further comprising press fitting the inner composite structural component and the outer cone section together.
 11. A method of manufacturing a sub-assembly for use with a frac plug or bridge plug system comprising the steps: forming a first structural component having a tapered body with a first composite material, forming a second component by molding for use with the first structural component, said molding comprising use of a second composite material; wherein the first structural component has a first open end with a first outer diameter, a second open end with a second outer diameter, and a bore extending between the first and second open ends; wherein at least one of the first structural component and the second component has a tapered surface section; and wherein the second outer diameter is larger than the first outer diameter.
 12. The method of claim 11, wherein the second component is located over the first structural component.
 13. The method of claim 12, wherein the molding step is either injection molding or compression molding a polymer material around a filament wound fiber material.
 14. The method of claim 11, wherein the molding step is performed separately from the first structural component.
 15. The method of claim 12, wherein the first structural component is made of carbon fiber or woven cloth and polymeric resin materials.
 16. The method of claim 11, wherein the forming step for the first structural component comprises winding a fiber material around a mandrel.
 17. The method of claim 16, wherein the second component is a cone section with a plurality of spaced apart fins. 